General manager Brian Cashman and manager Joe Girardi have been reluctant to name David Robertson as the Yankees new closer, and though Mariano Rivera would like Robertson to get his old job, he isn’t shocked the Yankees are looking around.

“It’s not surprising,” Rivera said of management’s refusal to hand the job to Robertson. “I guess they want to make sure they explore [other possibilities].”

With more established closers such as Grant Balfour, Joe Nathan, Joaquin Benoit, Fernando Rodney and Joel Hanrahan available, the Yankees could look for a backup plan.

It’s not a situation Rivera had to deal with when he took over after John Wetteland left following the 1996 season.

“I knew because they called me,” Rivera said Wednesday at a fund-raiser for the New Rochelle Fund for Educational Excellence at The Fountainhead in New Rochelle.

“I wasn’t waiting,” Rivera said. “I knew what I had to do.”

Despite the uncertainty surrounding the situation, Rivera said he believes his former setup man can succeed in a new role.

“If I’m David, you have to compete, work and be ready for any situation,” Rivera said. “Hopefully they give him the job and he can do it. But he doesn’t control that.”

Robertson occasionally has had difficulty when filling in for Rivera, including in 2012, as the Yankees eventually turned to Rafael Soriano after Rivera was lost for the season with a torn ACL.

“David has the pitches,” Rivera said of being able to transition from the eighth inning to the ninth. “But it’s the Yankees’ decision.”

Rivera recalled his own struggles from the early part of the 1997 season.

“You cannot [judge] a pitcher on five or three or two outings,” Rivera said.

“As a matter of fact, I blew three or four saves the first week, so if they had given up on me, we would have never had all this.”

Rivera did blow three of his first six save opportunities that season before finding his form.

“Everything is a chance you take,” Rivera said of Robertson potentially becoming the closer. “You don’t know how you’re going to respond.”